We propose to test the hypothesis that a computer programmed to interact in dialogue can provide direct assistance to patients with important, common medical problems. We have chosen urinary tract infection, sore throat, hyperlipoproteinemia and headache for our preliminary experiments, because these disorders are representative of problems that require individualized attention too complex for pamphlets and books. Professional help, which is traditionally required for these problems, is sometimes unavailable and always expensive. We hope to prove that the automated patient's assistant can be effective, thorough and inexpensive and provide a supportive, personalized attention sometimes missing from the busy clinical situation. For each of these disorders, the specifics of treatment will be determined by the patient in consultation with the computer. The program will offer information and suggestions, answer questions, provide advice about how to take medications, test for comprehension, print prescriptions, schedule follow-up visits, generate progress notes, and store data for subsequent research. The patient will be in control of the process, making decisions on the basis of information provided in the interaction. It is our hypothesis that patients will elect to make their own medical decisions and will be more faithful to them than to the dictates of their physicians (1,2). Furthermore, we believe that patient-computer dialogue will provide new insights into the process of clinical interviewing.